Minor Native Client specific changes to files in src.

Minor Native Client specific changes to files in src.

These changes are required for Native Client validation and to
accomodate the limitations of the NaCl runtime.

BUG=2614
Committed: https://code.google.com/p/v8/source/detail?r=14187

[Brad Chen, 2013-04-05 04:00:47]

PTAL

[ulan, 2013-04-08 11:27:10]

https://codereview.chromium.org/13704002/diff/1/src/platform-linux.cc
File src/platform-linux.cc (right):

https://codereview.chromium.org/13704002/diff/1/src/platform-linux.cc#newcode...
src/platform-linux.cc:1084: // Profiling is disabled for x86_64 Native Client.
Is this #ifdef needed because of undefined ucontext_t compile errors on
nacl_x64? It might be better to define ucontext_t as we do above for ANDROID.

[Brad Chen, 2013-04-08 16:29:56]

https://codereview.chromium.org/13704002/diff/1/src/platform-linux.cc
File src/platform-linux.cc (right):

https://codereview.chromium.org/13704002/diff/1/src/platform-linux.cc#newcode...
src/platform-linux.cc:1084: // Profiling is disabled for x86_64 Native Client.
On 2013/04/08 11:27:10, ulan wrote:
> Is this #ifdef needed because of undefined ucontext_t compile errors on
> nacl_x64? It might be better to define ucontext_t as we do above for ANDROID.

No, in this case the problem is more fundamental, that Native Client doesnt'
support exception handling, which appears to be required for profiling support.
I will improve the comment.

[Brad Chen, 2013-04-08 16:38:32]

https://codereview.chromium.org/13704002/diff/1/src/platform-linux.cc
File src/platform-linux.cc (right):

https://codereview.chromium.org/13704002/diff/1/src/platform-linux.cc#newcode...
src/platform-linux.cc:1084: // Profiling is disabled for x86_64 Native Client.
On 2013/04/08 16:29:56, Brad Chen wrote:
> On 2013/04/08 11:27:10, ulan wrote:
> > Is this #ifdef needed because of undefined ucontext_t compile errors on
> > nacl_x64? It might be better to define ucontext_t as we do above for
ANDROID.
> 
> No, in this case the problem is more fundamental, that Native Client doesnt'
> support exception handling, which appears to be required for profiling
support.
> I will improve the comment.

It might be possible to get this code to compile using the approach used with
ANDROID, but because of the signal handling issues it would not run. I will
change the #ifdef to disable for Native Client on all platforms. Okay?

[ulan, 2013-04-09 07:38:18]

> I will change the #ifdef to disable for Native Client on all platforms. Okay?
OK, sounds good.

[Brad Chen, 2013-04-09 14:59:19]

On 2013/04/09 07:38:18, ulan wrote:
> > I will change the #ifdef to disable for Native Client on all platforms.
Okay?
> OK, sounds good.

PTAL

[ulan, 2013-04-09 15:05:29]

LGTM, I will land it for you.

[ulan, 2013-04-09 15:12:19]

Committed patchset #2 manually as r14187 (presubmit successful).